Which security control restricts access to a website for a specific user group?

• A. Blacklisting
• B. Whitelisting
• C. Cryptography
• D. Substitution Cipher

Answer: (A)

Blocking access to a website for certain users is governed by a deny-list approach, known as blacklisting. A blacklist lists the users or groups that are not allowed to connect, so adding a specific user group to that list directly denies their access while others can still reach the site. This matches the idea of restricting access for a particular group. Whitelisting, by contrast, would allow only explicitly approved groups and block everyone else, which is a different way of enforcing access. Cryptography and a substitution cipher are about protecting or disguising data, not controlling who can access a web resource.